Poly(maleic acid) sulfonates and their production

ABSTRACT

Poly(maleic anhydride)s are sulfonated to produce more soluble detergent builders without loss of detergency building properties.

(54] POLY(MALEIC ACID) SULFONATES AND THEIR PRODUCTION 5 Claims, No Drawing:

[521 US. Cl 260/784 R. 252/151. 260/793 R. 260/79.5 NV

- v.-. mu". I" 3,624,048

[72] Inventors John H. lhlllbtrp [5i 1 III. Cl. C08! 27/06, m luua m; c0sr29/34 John J. RinmTmlomN-J4MG. [$0] l' ielddscarch 260/784 R. MncKellu, Ylrdlry. Pa. 78.5 T. 79.5 NV. 79.3 R

[2| 1 Appl. No. 38,556

22] Filed m 18,1970 1 Mm 451 Patented Nov. 30, 1971 uurnsn STATES PATENTS l W 3.490.150 2/l970 Kropp zoo/78.4 3.557.065 l/l97l Blumbcrg a al 260/784 Primary Examiner-Joseph L. Schofcr Assistant Examiner-John Kight, III Attorneys-Milton Zucker. Frank lanno and Eugene G. Seems ABSTRACT: Poly(malcic anhydride)s are sulfunaled to gency building properties.

POLY(MALEIC ACID) SULFONATES AND THEIR PRODUCTION Background of the Invention The commonly used detergent compositions include soaps and synthetic detergents, mixed with compounds known as builders, which act both to improve the detergent power of the primary detergents, and to reduce the cost of the overall compositions. The inorganic polyphosphates, such as sodium and potassium tripolyphosphate, have been almost universally used as the bulk of the builder constituents in such compositions. However, there has been a growing resistance to the use of polyphosphates, on the ground that they induce the buildup of undesirable vegetation in waters into which the detergents wastes are eventually discharged, and there has been a growing demand for detergent builders which would not cause this difi'iculty. Any such detergent builder must, of course, have optimum economics, and should not produce different environmental hazards than do the phosphates.

Many such builders have been suggested, but all have sub stantial disadvantages. Nitrilotriacetic acid, which is currently being used commercially as a substitute for phosphates, is both more expensive and potentially dangerous, in that it can keep quantities of heavy metals in solution in water. Other available builders are either much more costly, or have other serious drawbacks.

A potentially interesting group of possible detergent builders comprises the alkali metal salts of poly(carboxylic acid )s as described in the Diehl U.S. Pat. No. 3,308,067 issued Mar. 7, 1967. This patent describes the use, as builders, of the water-soluble salts of poly(carboxylic acid )s, the simplest and least expensive of which are the sodium salts of various poly(maleic acid )s. Unfortunately, the usefulness of these products is limited, particularly with the higher-molecularweight products, by their difficult solubility in cold waterthey all dissolve too slowly to be satisfactory and are limited in practical use to hot-water detergents.

STATEMENT OF THE INVENTION We have discovered new detergent builder materials which are sulfonated poly(maleic acid)s with a chain length of at least 3 maleic units, or chlorinated or hydroxylated derivatives thereof preferably in the form of water-soluble salts thereof.

The sulfonation of poly(maleic anhydride) followed by hydrolysis to poly(maleic acid) results in compounds whose alkali metal, ammonium, and quaternary ammonium salts, even when halogenated or hydroxylated, are much more water-soluble than the unsulfonated products, while, quite surprisingly, the calcium-sequestering and detergent powerscommon measures of builder activity-are affected to a minor degree, beginning to fall off notably when the SC I-I group represents about l percent by weight of the polyacid.

DETAILED DESCRIPTION OF THE INVENTION The starting point in the production of the products of this invention is maleic anhydride.

Polymerization of the anhydride may be carried out according to the method described in the Berry US. Pat. No. 3,359,246 issued Dec. 19, 1967, or it may be, and preferably is, done in accordance with the methods described in the Blumbergs et al. applications Ser.. No. 758,678 filed Sept. l0, l968 and Ser. No. 862,059 filed Sept. 29, I969.

The polymerization is carried out to produce a material in which there is at least an average of three units per molecule, and is preferably carried out to a much higher degree-typically to a molecular weight in the range of 5,000 or higher. Water solubility decreases as molecular weight increases; however, when sulfonation is carried out to higher levels, appreaching 9 to l0 percent high molecular weight no longer is a problem, so there appears to be no upper limit within the limits in molecular weight set by the polymerization technique itself.

The polymer is sulfonated in known fashion. We may use SO, gas in an inert solvent, using the general reaction described by Gilbert et aL-Industrial 8t Engineering Chemistry, Vol. 49, p. 2,065ff.or we may use a dioxane-SO complex, following the general procedure outlined by Suter et aL-Joumal of the American Chemical Society, Vol. 68, p. 538ff.

In a typical method, the polymer is dispersed or dissolved in a solvent resistant to SO -cg. a perhalogenated solvent-and then treated with S0, gas to cause sulfonation to take place. Below 0 C., sulfonation is rather slow, and refrigeration expensive; while reaction is feasible, we prefer to operate above this temperature. Above about 20 C., some discoloration of the product occurs, so that we prefer to keep temperatures down to this figure. However, the reaction can be carried out outside of this range of about 0-20 C., with only the indicated disadvantages.

The sulfonated poly(maleic anhydride) may be hydrolyzed with water to form poly( maleic acid) or neutralized with an alkali to form a water-soluble salt of poly(maleic acid). Suitable alkalis are the alkali metal hydroxides and carbonates, ammonium hydroxide, and quaternary ammonium compounds.

About 1 percent of 50;, by weight, gives a threefold increase in cold-water solubility to a typical sodium polymaleate, with no noticeable change in calcium-sequestering ability or detergent builder efficiency. At about l0 percent of SOJ-I, the calcium-sequestering power of the product begins to fall off, so that we prefer not to use higher degrees of sulfonation than about l0 percent.

Our preferred product, because of cost, is sulfonated poly(maleic acid). However, tests indicate that similarly good results are obtained with halogenated and hydroxylated poly(maleic acid) sulfonates. Simple halogenation produces the halogenated derivative. The hydroxy derivative is obtained from the halo derivative by dehydrohalogenation, epoxidation and opening of the epoxy group to hydroxyls.

In the salt form of the product, the sodium salts are preferred, for obvious cost reuons; but the other alkali metal salts are also effective builders, as are the ammonium and quaternary ammonium salts. The acid form of the compounds may be used directly in commercial laundering operations, using an alkali such as soda ash along with it to promote solubilization. For packaged detergents, it is obviously most effective to use the water-soluble salt form.

SPECIFIC EXAMPLES OF THE lNVENTlON The following specific examples of the invention are given by way of illustration and not by way of limitation.

EXAMPLE 1 Ten grams of poly(maleic anhydride), obtained by homopolymerization of maleic anhydride to a molecular weight of about 7,000 was placed in a 250 ml. 3 -neck flask, equipped with a laboratory stirrer, thermometer, condenser and a gas inlet tube. The flask was cooled in an ice water bath and 200 ml. of tetrachloroethylene solvent was added. The reaction mixture was stirred and SO, gas was introduced into the flask through the gas inlet tube at a rate of approximately 1 gram in 20 minutes. The reaction mixture was maintained at 2-6 C. during the SO; feeding time. After 1 gram of S0 was added, the reaction mixture was stirred and maintained at 2-6 C. for an additional 60 minutes.

The reaction mixture was then filtered, the solids on the filter were washed 3 times with fresh tetrachloroethylene solvent, and were dried under reduced pressure. There was 10.7 grams of poly(maleic anhydride) sulfonic acid obtained.

The product was dissolved in I00 ml. of distilled water and was neutralized with 10 percent NaOH solution to pH 10.0. The mixture was then evaporated to dryness under reduced pressure, giving l6.3 grams of sodium polymaleate sulfonate product. The elemental analyses showed 3.2 percent sulfur content, which corresponds to ID percent by weight of S0,Na groups present in the product.

The sodium polymaleate sulfonate product was evaluated as a detergent builder material by determining the solubility in water. calcium-sequestering value, and detergent builder efficiency. compared with sodium tripolyphosphate.

The results are listed in table l. 5

Table l Sodium Polymaleate Sulfonate Evaluation Results Under the evaluation conditions as seen in table: 1, the sodium polymaleate sulfonate was considerably better detergent builder material than sodium tripolyphosphate, used recently in commercial detergent formulations. Also, calciumsequestering value was considerably higher.

The calcium-sequestering value is determined by titrating a sample of the product with a calcium acetate solution, using an electrode sensitive only to calcium ions; the end point is reached when the presence of calcium ions is indicated.

The measure of detergent builder efficiency is arbitrary. Soiled cotton cloth is washed with a standard detergent formulation using sodium tripolyphosphate as the builder, with water at 150 p.p.m. calcium hardness; the resultant fabric is used as a standard. The same fabric is then washed with the same standard detergent formulation, using various builders, with waters at 300 p.p.m. calcium hardness. The efficiency is reported as percentage of brightness of the sample compared with the standard. Note that sodium tripolyphosphate is only about 80 percent as effective at 300 p.p.m. calcium hardness as it is with water at I p.p.m. calcium hardness.

EXAMPLE 2 Several samples of sodium polymaleate sulfonates were prepared by the procedure described in example i. Various amounts of sulfonic groups were added and samples were evaluated the same way as described in example I. Also, sodium salt of the poly(maleic anhydride) was made, which was used as the starting material in these preparations. Sodium tripolyphosphate was used as the blank. The results are listed in table 2.

TABLE 2.-EFFECT OF SULFONATION Calcium- 1 Test conditions-wash water hardness, 300 p.p.m., temperature, 120 F, detergent builder concentration in formulation, 50%.

1 Sodium polymaleate.

it will be noted that the water solubility of our products compares most favorably with the polyphosphate. so that they can be used as complete replacement for it. The unsulfonated polymaleate, because of its low solubility at room temperature. is useful only in hot-water washing, where its solubility is much better.

EXAMPLE 3 Ten grams of poly( maleic anhydride) was sulfonated with S0; gas in tetrachloroethylene solvent the same way as described in example I. Afier separation of the product by filtration and washing with fresh tetrachloroethylene, there was collected l0.6 grams of poly(maleic anhydride) sulfonic acid product. The product was dried under reduced pressure to remove the rest of solvent and then it was dissolved in lOO ml. of distilled water.

The water solution was placed in a 250 ml. 3 -neck flask, equipped with a laboratory stirrer, thermometer, condenser and gas inlet tube. Then chlorine gas was introduced into the flask through the gas inlet tube. Chlorination was continued until approximately 3.0 grams of Cl, was consumed. Then the reaction mixture was concentrated under reduced pressure to remove all the l-lCl formed as a byproduct in chlorination. The W solution was cooled to 0-5 C. and was neutralized carefully with 10 percent NaOl-l solution until a pH of I00 was reached. The solution turned brown at this point, probably due to some double-bond formation. Sodium hypochlorite was used to bleach the solution. Then it was evaporated to dryness in a Rinco evaporator under reduced pressure. There was obtained 18 grams of sodium chloropolymaleate sulfonate product, containing 14.6 percent by weight of chlorine and 9.2 percent by weight of sulfonic acid groups.

The product was evaluated as a detergent builder by the same procedures described in example I. The results are shown in table 3.

TABLE 3.-8ODIUM CHLOROPOLYMALEATE SULFONATE 1 Sodium chloropolyrnaleate sullonate obtained in Example 3.

EXAMPLE 4 Ten grams of poly(maleic anhydride) was sulfonated with S0; gas in tetrachloroethylene solvent the same way as described in example I. The product was chlorinated in water solution with Cl, gas as described in example 3. in this experiment, the product after chlorination was treated with triethylamine to dehydrochlorinate the product. This can be illustrated by the following formula:

{COOK COOH COOH C00H\ Hi :)i ll OtH I I trlethylamlne COOH COOH COOH COOH\ -+(CH;CHi)aN.HCl

\ OiH 1 1 trlathyiamine hydrochloride The triethylamine hydrochloride was removed by washing the dry product with chloroform solvent. The dark brown product was dissolved in water. was neutralized with NaOH solution to pH l0 and was hydroxylated with H,O, solution at pH until all the double bonds disappeared. This reaction can be illustrated by the following equation:

COONa COONa 000m 000m 5 {I l l epoxidatlon c 0 +H:0r-

\ SOrNa H /n hydrolysis EOONB (JOONB (IJOONB (l300Na\ The reaction mixture was then evaporated to dryness in a Rinco evaporator under reduced pressure to yield l8 grams of white solids which analyzed as follows:

Found:

Calc.:

The product was identified as sodium polyhydroxy maleate sulfonate. It had a calcium-sequestering value of 16.8 g. Call 00 g. of product. water solubility at room temperature 8.7 percent by weight and detergent builder efficiency of 96 percent Obviously. the examples can be multiplied indefinitely without departing from the scope of the invention as defined in the claims.

What is claimed is:

l. A compound selected from the group consisting of sulfonated poly(maleic acid) with a chain length of at least three maleic units and containing l to I0 percent SO H, and chlorinated and hydroxylated derivatives thereof.

2. A detergent builder consisting essentially of an alkali metal, ammonium or quaternary ammonium salt of a compound in accordance with claim 1.

3. The composition of claim 2 in which the salt is of sodium.

4. Sulfonated poly(maleic acid) with a chain length of at least three maleic units and containing 1 to l0 percent SO H.

5. A detergent builder consisting essentially of the sodium salt of the sulfonated poly(maleic acid) of claim 4.

i t t I i 

2. A detergent builder consisting essentially of an alkali metal, ammonium or quaternary ammonium salt of a compound in accordance with claim
 1. 3. The composition of claim 2 in which the salT is of sodium.
 4. Sulfonated poly(maleic acid) with a chain length of at least three maleic units and containing 1 to 10 percent SO3H.
 5. A detergent builder consisting essentially of the sodium salt of the sulfonated poly(maleic acid) of claim
 4. 